Brake



Jan. 30, 1940.

C. H. BOCK BRAKE Filed oct. 8, 1937 2 Sheets-Sheet 1 20 /2 20 J. Z 4 INVENTOR.

i 5Z- Z BY Czaef/vcf H Bac/r f 7W @www 7m ATTORNEYS.

Jan. 3o, 1940. c, H BOCK i 2,188,453

BRAKE Filed Oct. 8. 1937 2 Sheets-Sheet 2 Y 'gg 6484 44 l Y "l r H 154' W 2i@- A W1 tgig ll' i i 1 N VE NTOR. 62. @e5/vea h. Bac/r ATTORNEYS.

Patented Jan. 30, 1940 UNITED STATES BRAKE Clarence H. Bock, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application October 8, 1937, Serial No. 167,921

4 Claims.

'Ihis invention relates to brakes for motor vehicles, and more particularly to a combined service and emergency brake.'

Broadly the invention comprehends a brake 6 having a duplex actuating means including a uid pressure means for actuating the friction `elements of the brake and mechanical means for actuating the same friction elements.-

In a preferred embodiment of the invention a fluid pressure actuated motor operative to move the friction elements into engagement with the drum includes means for inhibiting retrograde movement of the fluid in the motor due to drum distortion, and the mechanical actuating means includes an assembly of an actuator and adjustable anchors for the friction elements.

An object of the invention is to provide a iiuid pressure actuated motor having means inhibiting retrograde movement of the fluid in the motor during energization thereof.

Another object' of the invention is to provide a brake having an auxiliary actuator for the friction elements of the brake arranged intermediate adjustable anchors for the friction elements and operative to apply force tothe friction elements through the anchors.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings forming a part of this specification, and in Which- Fig. 1 is a vertical sectional view of the brake just back of the head of the drum illustrating the invention as applied;

Fig. 2 is a sectional view substantially on line 2 2, Fig. 1; T

Fig. 3 is a sectional view substantially on line 3 3, Fig. 1;

Fig. 4 is a sectional view substantially-on line 4 4, Fig. 1;

"Fig 5 is alongitudinal sectional view of the fluid pressure actuated motor;

Fig. 6 is a sectional vie'w substantially on line 5 6, Fig. 5;-

Fig. '7 is a sectional view substantially on line 1 1, Figb; and

Fig. 8 is a sectional view substantially on line 8 8 Fig. 5.

Referring to the drawings for more specific details of the invention, I0 represents a fixed support or backing plate adapted to be secured to an axle or to an axle housing. The backing plate has associated therewitha rotatable drum I2 adapted to be secured to a wheel, and a pair of corresponding interchangeable friction ele- (o1. isa-'106) ments or shoes I4 and I6 are mounted on the backing plate for cooperation with the drum.

The brake shoe I4 is a forward braking shoe and the brake shoe I6 is a trailing brake shoe. Each of the braking shoes includes a web, I8 sup- 5 porting a rim 2,0 having secured thereto a suitable lining 22 for frictionally engaging the drum. An assembly f an auxiliary actuating means and adjustable anchors indicated generally at 24 is mounted on thebacking plate. The anchors of l0 this assembly receive the articulate ends of the shoes I4 and I6, and corresponding oppositely disposed adjustable anchors 26 regulated by a turn buckle 28, also mounted on the backing plate, receive the separable ends of the shoes.

A retractile spring `lill connects the shoesadjacent their articulate ends, and a corresponding retractile spring 32 connects the shoes adjacent their separable ends. These springs serve to return the shoes from their applied positions to 20 their retracted or oft' positions, and to retain the shoes when in their retracted positions against the anchors of the assembly 24 and the anchors 26, where they are supported in proper spaced relation to the drum. i

The prime actuator for the brake includes a fluid pressure actuated motor 34 mounted on the backing plate between and connected to the separable ends of the shoes I4 and I6. The motor comprises a cylinder 36 having a large chamber 80 38, a relatively small chamber 4I), and an inter- Y mediate chamber 42, all concentric to and communicating with one another.

One end of the intermediate chamber 42 opens directly into the large chamber 38, and at the 85 junction of the large and intermediate chambers is an annular shoulder 44. The other endof the intermediate chamber is closed asv by a head 46 having an axial port 48 providing a communication between the intermediate and the small 40 chambers.

The -large chamber 38 has a port 5I) connected as by a fluid pressure delivery tube 52 to a suitable source of fluid including a iluid pressure producing device. The chamber 38 also has a 45 port 54 normally closed as by a bleeder screw 56, and, correspondingly, the small chamber 40 has a port 58 normally closed as by a bleeder screw60.

Oppositely disposed pistons 62 and 64 reciprocable in the large chamber 38 have upon their 50 respective heads sealing cups 66 and 68, one of which, the cup 68, has an axial opening. A spring 18 interposed between the cups serves to .retain thev cups against displacement and also' to retain the pistons in proper spaced relation 66 mounted in the block |26 provides an anchor forY the articulate end of the forward braking shoe to one another when in retracted position, and a spring 12 interposed between the back of the piston 64 and the annular shoulder 44 normally,

urges the piston 64 against a stop 14, and arranged inthe Wall of the cylinder adjacent the annular shoulder is an air vent 16.

The piston 62 has in its 4back a recess 18 receiving one end of a thrust pin 80. end of the thrust pin is suitably connected to the forward braking shoe I4, and a shield 82 sleeved on the thrust pin embraces the open end of the large chamber 38 for the exclusion of dust and other foreign substances from the cylinder.

The piston 64 has a concentric extension 84 movable in the intermediate chamber 42, and this extension has a reduced end portion 86 provided with an annular shoulder 88 and a frustroconical end 90 adapted to enter and close the port 48. A sealing cup 92 sleeved on the reduced portion 86 and seated on the extension 84 is held against displacement by the annular shoulder 88. The piston 64'has an axial passage 94 extending therethrough, and in this passage is a valve chamber 06 having therein a springpressed ball valve 98 for controlling the passage. The piston also has a plurality of spaced passages |00 extending therethrough.

A piston |02 reciprocable in the small chamber 40 has on its head a sealing cup |04, and a spring |06 interposed between the cupi and the head 64 serves to retain the cup against displacement and also to retain the piston in proper spaced relation to the head 46 when the piston is in its retracted position. A recess |08 in the back of the piston |02 receives one end of a thrust pin I I 0. The other end of the thrust pinis suitably connected to the trailing brake shoe I6; and a shield I|2 sleeved on the thrust pin embraces the ope'n end of the chamber 40 for the exclusion of dust and other foreign substancesfrom the chamber.

The assembly of the auxiliary actuator and adjustable anchors indicated generally at 24 includes a plate I| 4 suitably secured to the backing plate. This plate has spaced openings I6 and I8 and an intermediate opening |20 registering with correspondingly arranged openings in the backing plate. The plate I|4 also has its respective ends channeled to provide oppositely disposed guide-Ways |22 and |24 having slidably mounted therein corresponding anchor I4, and a similar adjustable eccentric I 32 mounted in the block |28 provides an anchor forthe articulate end of the trailing brake shoe I6.

The eccentrics are accessible through the openl |40 having thereonacam |42 disposed between the anchor blocks |26 and |28. A .plate or washer |44 suitably secured on the shaft and fiapped against the anchor blocks serves to re-v tain the anchors .a'gainst displacement. The

shaft extends beyond the sleeve for the reception of an operating lever |46 connected as by a rod |48 to a suitably actuating lever, not shown.

The other In a normal operation, when used as a service brake, upon energization of the fluid pressure actuated motor 34, uid under pressure entering the large ychamber 38 of the cylinder 35l causes movement of the piston 62 on its compression stroke, resulting in actuation of the forward causing movement of the piston |02 on its compression stroke, resulting in actuation of the trailing brake shoe I6.

As the pistons 62 and |02 move on their compression strokes, the piston 64 also moves against the resistance of the spring 12 and seats the conical end on the extension 84 of the piston 64 in the port 48, and thereafter, as the pressure on the fluid in the large chamber 38 builds up, fluid is displaced from the large chamber through the passage 94, past the valve 98 in the piston 64, into the small chamber 40. n

Under these conditions, should the drum expand due to heat generated in a braking operation, the iiuid in the small chamber becomes trapped and maintains a constant pressure in the small chamber, tending to retain the piston |02 against movement. This results in retaining the trailing shoe I6 against movement toward its retracted position, and, accordingly, checks distortion of the drum.

`Upon release of the brake the pistons'62 and |02 are moved to their retracted positions and the fluid in the cylinder is returned to the source of supply under the influence of the retractile spring 32 connecting the shoes I4 and I6. Simultaneously with this movement of the pistons 62 and |02, the piston 64 moves to its retracted position under the influence of the spring 12, and this movement of the piston 64 results in opening the port 48 and establishing communication between the chambers 38, 40 and 42 of the cylinder.

When operated as an emergency or parking brake, force is applied to the lever |46 through conventional linkage including a hand lever, not shown, and a pull rod |48. 'I'his results in moving the lever |46 through an angle, and this movement of the lever'is transmitted to the operating shaft |40 and the cam |42 on the shaft. Upon this movement of the cam, force is transmitted therefrom in opposite directions to the slidable anchor blocks |26 and |28, resulting in spreading the anchor blocks apart, and, accordingly, moving the shoes I4 and I6 adjustably connected to theblocks into engagement with the drum.

At the conclusion of a braking operation, the applied force on the leverY |46 is released and the lever is returned to its retracted or normal position under the inuence of a retractile spring, not shown. As the lever I 46 returns to its normal position, the cam also returns to its normal position, and, as'the cam returns, the slidable anchor blocks |26 and |28 are urged by the retractile spring 30 to follow the cam, and, accordingly,the shoes |4 and I6 anchored on the anchor blocks are moved to their retracted positions.

Although this invention has been described in connection with certain Vspecific embodiments, .Y

the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is.

therefore, to be limited only by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is- 1. A brake comprising a pair of corresponding friction elements, an adjustable anchor connected between adjacent ends of the elements, slidable anchor blocks adjustably connected to the other ends-of the elements, and a cam. intermediate the blocks.

2. A brake comprising a pair of corresponding friction elements, an adjustable anchor connected between adjacent ends of the elements, slidable anchor blocks adjustably connected to the other ends of the elements, a cam intermediate the anchor blocks, and a uid pressure actuated motor connected between the elements.

3. A brake comprising a pair of corresponding interchangeable friction elements, an adjustable anchor including a turn buckle connecting adjacent ends of the friction elements, slidable anchor blocks adjustably connected to the other ends of the friction elements, guide-ways for the anchor blocks, a cam intermediate the anchor blocks, and a fluid pressure actuated motor con- CLARENCE H. BooK. 20 

